I purchased a Kantronics KAM98 from the list here. I was doing good and had the unit up and running and exercising the modes. Approx two hours in, the TNC locked up and stopped communicating with the terminal Did a series of hard resets to no avail. Not even a bar indicator light. No RS232 control either and I tried a bunch of terminal programs. To be fair to the seller, he did say it powered on but no testing. So its on me to get it fixed. I started to change the CAPs on the board C99 10uF in the 5vdc regulator circuit first off. I have a solid 4.97vdc at the test points. But still no joy in bringing up the unit. Next I will change out C35 1uF and C61 47uF and that should take care of the polarized CAPs. Since my terminal programs are not talking to the TNC, I was thinking of changing out the RS232 Converter IC next [ADM208EANZ]. The non-Z are no longer available. I was also looking for a eprom v8.3 replacement in case mine was corrupt. Oh, I did validate all 26 Jumpers. Anyone with experience troubleshooting these units input would be welcome.